In lenticular type three-dimensional (3-D) photography, a plurality of two-dimensional (2-D) views of the scene are taken from a number of horizontally spaced vantage points and the series of 2-D images is then compressed and printed at the focal plane of each of the lenticules of the lenticular screen to form a 3-D composite image of the field.
In the past, a minimum of four 2-D views were used to compose a 3-D picture and each of the plurality of compressed 2-D lineiform image bands occupied an equal width in the lenticule. An even number of image bands was also always used. Several images may be printed within a single band. This has commonly been referred to as W/N, wherein "W" is the width of each lenticule and "N" is the number of 2-D image bands to be used in the total composition, and the lineiform image bands of the stereo pairs are arranged in a symmetrical relationship to the center of the curvature of the lenticular screen of the lenticule.
When a person is viewing a 3-D photograph, the ideal situation is for the eyes to see a stereo pair of adjacent 2-D lineiform image bands. Thus as illlustrated in FIG. 1, the eyes should see image bands 1 and 2, 2 and 3 or 3 and 4 so that the proper parallax between the pair of 2-D images can be maintained in order to construct a 3-D image that is in focus and not blurred. Parallax is the apparent shift in position of an element of an object field due to the relative change in position of the element and the place from which the element is viewed. In viewing three dimensional photographs of the past, the eyes do not always see the stereo pair formed by the adjacent 2-D image bands. Frequently, the eyes will see non-adjacent stereo pairs formed by image bands 1 and 3, 2 and 4, or 1 and 4 as shown in FIG. 1 according to the angle and the distance of viewing the photograph. When the eyes see a stereo pair where the image bands are non-adjacent, they do not fuse the pair of images together to form a solid image because of the excessive parallax between them.
The minimum number of 2-D views used to compose 3-D photographs of the past is four with the normal viewing angle of the lenticule of the print material being from approximately 20 to 30 degrees. Consequently, each 2-D image band covers an angle of less than 71/2 degrees. At a normal viewing distance of 15 inches, the eyes will view through an angle of approximately 10 degrees of the lenticule. Unless the 3-D photograph is held exactly at the center between the eyes and perpendicular thereto, the eyes will see a non-adjacent stereo pair which will be formed by image bands 1 and 3, 2 and 4, or 1 and 4 as shown in FIG. 1, 2 and 3.